1 files changed, 71 insertions, 0 deletions
diff --git a/trunk/codecs/ilbc/anaFilter.c b/trunk/codecs/ilbc/anaFilter.c
new file mode 100644
index 000000000..f88fefaa0
--- /dev/null
+++ b/trunk/codecs/ilbc/anaFilter.c
@@ -0,0 +1,71 @@
+
+/******************************************************************
+
+    iLBC Speech Coder ANSI-C Source Code
+
+    anaFilter.c 
+
+    Copyright (C) The Internet Society (2004). 
+    All Rights Reserved.
+
+******************************************************************/
+
+#include <string.h>
+#include "anaFilter.h"
+#include "iLBC_define.h"
+
+/*----------------------------------------------------------------*
+ *  LP analysis filter.
+
+
+ *---------------------------------------------------------------*/
+    
+void anaFilter(
+    float *In,  /* (i) Signal to be filtered */
+    float *a,   /* (i) LP parameters */
+    int len,/* (i) Length of signal */
+    float *Out, /* (o) Filtered signal */
+    float *mem  /* (i/o) Filter state */
+){
+    int i, j;
+    float *po, *pi, *pm, *pa;
+
+    po = Out;
+
+    /* Filter first part using memory from past */
+    
+    for (i=0; i<LPC_FILTERORDER; i++) {
+        pi = &In[i];
+        pm = &mem[LPC_FILTERORDER-1];
+        pa = a;
+        *po=0.0;
+        for (j=0; j<=i; j++) {
+            *po+=(*pa++)*(*pi--);
+        }
+        for (j=i+1; j<LPC_FILTERORDER+1; j++) {
+
+            *po+=(*pa++)*(*pm--);
+        }
+        po++;
+    }
+
+    /* Filter last part where the state is entierly 
+       in the input vector */
+
+    for (i=LPC_FILTERORDER; i<len; i++) {
+        pi = &In[i];
+        pa = a;
+        *po=0.0;
+        for (j=0; j<LPC_FILTERORDER+1; j++) {
+            *po+=(*pa++)*(*pi--);
+        }
+        po++;
+    }
+
+    /* Update state vector */
+
+    memcpy(mem, &In[len-LPC_FILTERORDER], 
+        LPC_FILTERORDER*sizeof(float));
+}
+
+